Switching device for electric motors



3 SheetsSheet 1.

(No Model.) I 8 v R. H. MATHER.

SWITGHING DEVICE FOR ELEGTRIG MOTORS. v No 882,715. 8 I Patented May 15,1888.

(No Model.) 3 SheefiSSheet, 2.

R. H. MATHER.

SWITCHING DBVIOE FOR ELECTRIC MOTORS. N0. 882,715; Patented May. 15,1888.

(No Model.) 3 Sheets-Sheet a.

ERMA-T EE."

SWITCHING DEVICE FOR'ELEGTRIG MOTORS.

No. 382,715. Patented May 15; 1888-.

UNITED STATES PATENT Crric e.

RICHARD H. MATHER, OF WINDSOR, CONNECTICUT.

SWITCHING DEVICE FOR ELECTRIC MOTORS.

SPECIFICATION forming part of Letters Patent No. 382,715, dated May15,1888.

Application filed February 19, 1887. Serial No. 228,251. (No model.)

To a whom it may concern.-

Be it known that I, Brennan H. MATHER, of Windsor, in Hartford county,Connecticut, have invented certain new and useful Improvements inSwitching Devices for Electric Motors, which are described in thefollowing specification, and illustrated by the accompanying drawings.

My invention-is designed to be used in connection with an electricmotor, particularly a series-wound motor, and an electric circuit ofconstant current, for the purpose of introducing such motor into suchcircuit gradually and without danger of sparking or of interrupting theconstancy of that current, and for the purpose of cutting said motor outof said circuit in a gradual and convenient manner. These objects Iaccomplish by means of a rheostat which is connected with the maincircuit and in parallel with the motor, and by means of certain contactsand connections which are adapted to introduce and to cutout successiveportions of the rheostat and at the same time to maintain themain-circuit connections of said motor.

The best manner in which I have contemplated applying the principle ofmy invention is shown in said drawings, in which- Figure 1 is a frontview of my invention. Fig. 2 is a section on x m of Fig. 1. Fig. 3 is asection on y y of Fig. 1. Fig. 4 is a detail. Fig. 5 is a back view ofmy inventi0n,the back side of the resistance-box being removed; and Fig.6 is a front view of said resistance-box and switch connected with aseries-wound electric motor.

In the views,the numeral 1 denotes the front side or cap of a wooden boxcontaining a rheostat, which is of any ordinary and convenientconstruction.

The numerals 2 to 15, inclusive, in Fig. 5 indicate the severalresistance'coils of said rheostat, which are connected in the usualmanner with each other, and with a number of brass studs or othercontacts, 16 to 30, in elusive, which pass through cap 1 and arearranged in the arc of a circle, as seen in Figs. 1 and 5. The aggregateresistance of said coils is greatly in excess of that of the electric motor which is to be used in connection therewith. Upon the face of cap 1,adjacent to in either direction.

said studs, but not in connection therewith, is acurved contact platehaving the form of a segment of a flat ring,which is concentric withsaid are. This plate is separated by a crosscut into two unequal parts,31 and 32. Holes 37 and 38 pass through plates 31 and 32. At the commoncenter of said are and ring, upon cap 1, is pivoted an arm orswitchfinger, 33, which is seen in detail in Fig. 3. This arm isprovided with a brush, 34, one end ofwhich, being wider than the spacebetween any two of said studs, which are adjacent to each other, isadapted to make successive contacts with all said studs, while the otherend of said brush is constantly in contact with one or the other of saidplates 31 and 32. Stop-pins 39 and 40 (seen in Fig. 1) are so placed asto prevent arm 33 from passing beyond said studs The free end of saidarm is provided with a spring-seated pin, 35, one end of which isprovided with a finger-piece, 36, while the other end of the same isadapted to press into holes 37 and 38 when arm 33 is deflected to itsextreme positions.

Just under hole 37 is a hole, 41, extending through cap 1. cap,near hole41,is mounted a cut-out magnet, 42, which is shown in Figs. 3, 4, and 5.This magnet, which is .wound in the usual manner with helix 43, isprovided with a-spring-seated armature, 44, which is armed with a detentor tooth, 45. This tooth, as seen in Fig. 3, is adapted to engage aninsulated spring, 46, which carries a contact, 47, adjacent to con tact48, and is provided with a stem, 49,which is partly within hole 41.Binding-posts and 51 are the terminals of the instrument.- The signsandin Fig. 6 may be regarded as the positive and negative terminals,respectively, of an electric generator. p

Such being the elements of my invention, the appropriate electricalconnections not already indicated are as follows: The positive terminalof said generator is connected with said motor by wire 52 and withterminal 51 by wire 53. Stud 16 is connected with terminal 51 by wire 54and with contact 48 by wire 55. Contact 47 is connected with plate 31 bywire 56. Terminal50 is connected with the negative side of saidgenerator by wire 57, with plate 31 by wire 58, and with said motor Uponthe under side of this duced.

by wire 63. Helix 43 is connected by shuntwires 59 and 60 with wires and56, respectively. Stud 16 is connected with resistancecoil 2 by wire 61and stud 30 with coil 15 by wire 62.

The remaining particulars of the construction and connection of thisinvention will sufficiently appear from its mode of operation, which isnow to be explained.

\Vhen arm 33 occupies its extreme position of contact with pin 39, brush34 makes contact with stud l6 and plate 31, while pin 35, entering hole37, as seen in Fig. 3, looks the switch closed. The current then passesfrom the positive side of the generator successively through wires 53and 54, stud l6, brush 34,

plate 31, wires 58 and 57 to the negative side of said generator, andthe motor is inactive. Vheu arm 33 is in the extreme position of contactwith pin 40, the poiutof the springseated pin 35 is held in hole 38, andthus said armis locked in that position. Brush 34 then rests upon stud30 and plate 32, and the current passes from terminal to terminal ofsaid generator by the way of wire 52, said motor, and wires 63 and 57.At the same time an insignificant portion of the current, which issupplied by the generator passes from terminal by wires 53, 54, 55, and59, helix 43, wires and 56, plate 31, and wire 58 to terminal 50. Whenarm 30 occupies an intermediate position, as in Figs. 2 and 5, one endof brush 34 rests upon plate 31, while the other end of the same restsupon one or two of said studs. In this position of affairs thedistribution of current is in two courses. One part of the currentpasses through the motor by way of wires 52, 63, and 57, while the otherpart of the same passes through a portion of said resistancecoils by theway of wires 53 54, brush 34, plate 31, and wires 58 and 57.

Assuming the switch to be in the position first above described, it itbe desired to intro duce said motor into circuit with the generator,said arm is unlocked from its position of contact with pin 39 bymanipulation of pin 35, and is slowly deflected by hand toward stoppin40. The resistances in the rheostat-circuit cause the motor to receive aslight current when the described motion of arm 33 begins. As the motioncontinues, a gradually-increasing number of said resistances is broughtinto circuit, and the motor is more and more energized until all saidresistances are intro- Then the connection between arm 33 and plate 31is broken, and the whole current passes through the motor. lVhen arm 33encounters pin 40, the rheostat is cut out of circuit, and pin 35,entering the hole 38, looks the switch, as above described. By unlockingthe switch and carrying arm 33 back to the position first abovementioned the switch is closed, and the current is permitted to pass int-hefirst-mentioned course through wires 53 and 54, stud 16, brush 34,plate 31, and wires 58 and 57.

In case of any accident, causing an interruption of current through themotor, the increase of current through helix 43, which is arranged inparallel with the motor, causes armature 44 to withdraw tooth 45 fromplate 47, and the latter, being thus released, is carried by theelasticity of spring 46 to contact with plate 48. The motor is thusshort circuited and the current passes between terminals 51 and 50 bywires 54 and 55, plates 48 and 47, and wires 56 and 58, and continues soto do until plates 47 and 48 are separated. Such separation occurs whenarm 33 is returned to the position shown in Fig. 3, being produced bythe pressure of pin 35 upon the end of stem 49. The cutout switch isthen locked in its original position by the action of the spring-seatedarmature 45, and the motor remains short-circuited through brush 34until the arm 33 is again deflected toward pin 40.

Disclaiming, for the purposes of this case, all things which are shownand claimed in my application, Serial No. 225,887, which was filedJanuary 29, 1887, for a patent upon switches for electric motors, Iclaim as my invention-- 1. An electric circuit, aseries-wound motor insaid circuit, a rheostat which is provided with a series ofcontact-points and is con nected with said circuitatone sideof saidmotor, a conductive plate which is connected with said circuit at theother side of said motor, a switch-finger which is adapted to makesuccessive contacts with said contact-points and to make and breakcontact with said plate, in combination with an automatic cutout whichis arranged as a shunt about said rheostat and motor, substantially asand for the purpose specified.

2. An electric motor, an automatic cut-out, a rheostat, and a manualswitch which is adapted to manipulate said rheostat, in combination withspring mechanism which is carried by the switch-arm and is adapted toopen said cut-out whenever said arm is carried to a predeterminedposition, substantially as and for the purpose specified.

3. An electric motor and a rheostat,in combination with a manual switchwhich has a movable switclrarm and is adapted to operate said rheostat,a spring-seated stop-pin which is carried by said arm, an automatic cutout which is provided with spring-contact, and an intermediate stemwhereby motion is communicated from said stop-pin to saidspring-contact, substantially as and for the purpose specified.

In testimony whereofl havehereunto set my name in the presence of twowitnesses.

RICHARD H. MATHER.

WVitnesses:

W. M. DYORKMAN, WVILLARD EDDY.

